Compute growing degree days by different methods for Parbhani location in rabi sorghum crop

The present study was conducted at the research farm of the Department of Agricultural Meteorology, Vasantrao Naik Marathwada Krishi Vidyapeeth, Parbhani, to examine the Effect of thermal regimes on rabi sorghum (Sorghum bicolor.L) varieties. The experiment followed a split-plot design with three replications. Three sowing dates were evaluated: D1 (42nd Standard Meteorological Week - SMW), D2 (43rd SMW), D3 (44th SMW). The study involved four sorghum varieties: V1 - Dagadi, V2 - Parbhani Moti, V3 -Parbhani Super Moti, and V4 - Parbhani Shakti. The crop was sown at a spacing of 45 × 15 cm, and the net plot size for each treatment was 4.5 × 2.1 m².Findings revealed that early sowing (D1) resulted in a longer crop duration from sowing to maturity compared to later sowing dates. Among the varieties, Parbhani Moti took the maximum number of days to reach maturity, followed byParbhani Super Moti, Dagadi and Parbhani Shakti.Accumulated thermal indices such as Growing Degree Days (GDD) were highest under the earliest sowing (D1), with a decreasing trend seen through D2 and D3. Among the varieties, Parbhani Moti recorded the highest values for GDD followed by, Parbhani Super Moti, Dagadi. Parbhani Shakti accumulated the least thermal units over the crop cycle.